1. Field of the Invention
The present invention relates to an engine cover for covering engines. In particular, it relates to a construction for installing an engine cover to engines.
2. Description of the Related Art
In the engine rooms of recent automobiles, it is general to dispose an engine cover above the engine and below the bonnet hood. The engine cover has a function of shielding noises emitted out from the engine (or transmission sounds) as well as a function of upgrading the decorativeness in the engine room by shielding the engine visually.
In general, an engine cover is installed to the cylinder head cover of an engine. In this instance, the engine cover is usually installed to the cylinder head cover by means of fastening with screw bolts, for example, as disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 2001-98,954. An engine cover disclosed in the publication is provided with through holes. A cylinder head cover, to which the engine cover is installed, is provided with threaded holes at positions corresponding to the through holes of the engine cover. When installing the engine cover to the cylinder head cover, screw bolts are fitted into the through holes of the engine cover from above, and are screwed into the threaded holes of the cylinder head cover. Thus, the fastening force exerted between the screw bolts and the threaded holes fastens the engine cover to the cylinder head cover.
However, it has been required recently to give automobiles a function of protecting pedestrians by reducing the shocks which automobiles exert pedestrians in collisions with human beings. For this purpose, the bonnet hood of an automobile is formed so as to deform in collisions with human beings, and the resulting deformation absorbs the shocks in collisions, in general.
In order to fully absorb the shocks in collisions by means of the bonnet hood's deformation, it is necessary to secure a space for permitting the bonnet hood to deform between the bonnet hood and the engine cover by placing the engine cover and the cylinder head cover close to each other in the up/down direction. However, when fastening the conventional engine cover to the cylinder head cover with the screw bolts as described above, the distance between the engine cover and the cylinder head cover might be enlarged because the length of the screw bolts determines the distance. Accordingly, there might arise a problem that it is difficult to provide the space for permitting the bonnet hood to deform to a satisfactory size.
A technology has been developed for solving the problem. In such a technology, an engine cover descends upon collisions, and approaches an engine, thereby securing a space for permitting a bonnet hood to deform between the bonnet hood and the engine cover, as disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 2004-204,709, for example.
The conventional engine cover disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 2004-204,709 comprises a collar, which is installed to a cylinder head cover, and a hollow member which is formed hollow and in which a fluid is sealed. Moreover, the collar is installed to the engine cover by way of the hollow member. The hollow member intervenes in the space between the cylinder head cover and the engine cover, and contacts elastically with them. Thus, the cylinder head cover and the engine cover are separated from each other.
Upon collisions, the collar fractures, the fractured collar breaks through the hollow member, and the fluid filled in the hollow member flows out. Accordingly, the fluid buffers the shocks resulting from collisions. Moreover, when the fluid filled in the hollow member flows out, the hollow member contracts so that the engine cover descends to approach the engine cover. Consequently, it is possible to secure a space for permitting a bonnet hood to deform between the bonnet hood and the engine cover.
However, the engine cover might be associated with a problem that the manufacturing cost goes up, because it requires many expensive component parts, such as the fracturable collar upon being subjected to a predetermined load, and the hollow member in which a fluid is filled.